Behavioural Ecology

Question 1

Tinbergen’s 4 questions about animal behaviour

Answer 1

1. Development ie does behaviour change through learning and growth
2. Mechanism (senses and physiology) eg do external factors affect behaviour changes
3. Adaptive function (contribution to survival and reproduction)
4. Evolutionary history (changes from ancestors) ie do the behaviours hint at history of organism

Question 2

ways of testing for heritability of behavioural traits (4 ways)

Answer 2

1. correlation between parents and offspring
   exps: blackcap bird migrations - offspring in captivity who were not trained by parents followed same patterns of direction and time
2. cross-breeding experiments
   exps: blackcap birds - hybrids fly in intermediate direction
   ALSO - hygienic behaviour in bees to avoid foulbrood epidemic - 2 alleles for hygienic beh found by crossbreeding
3. artificial selection experiments
   exps: human selection for cricket singing behaviours (divergence after only 4 generations)
   ALSO - dogs are bred for behaviours as well
4. molecular genetics
   exp: transferring vasopressing recptor (aka “social”) gene from social prairie voles to solitary meadow voles –> made them social!

Question 3

behavioural ecology

Answer 3

the study of the adaptive benefits of behaviour

implies that behaviour can evolve

also, allows for the examination of the history of behaviours (since bahviour does not fossilise, this is done through comparison to similar species, which suggest a POSSIBLE sequence of behavioural evolution) - see balloon fly

Question 4

possible evolution of balloon fly courtship (males must present females with a silken balloon, which serves no practical purpose)

Answer 4

[each of these behaviours is performed by extant species of empidid flies]

1. male searches for female alone
2. gives food to female - as a distraction or allows for longer period of copulation…?
3. Wraps food in silk (to further prolong process)
4. suck prey dry before wrapping
5. wrap insect fragment in silk, which is not eaten (cf current process in nectar feeding empidid flies)
6. finally, present empty silk balloon

Question 5

three methods to study adaptive questions about behaviour

Answer 5

1. observation
2. experiment

• first two, cf SIberian Jays experiment about maximising feeding of chicks and minimising of predation of parents

3. optimality modelling:
   - based on making predictions about the optimal (best) behaviour, and testing these predictions with observations and experiments.
   - If the animal behaves as predicted, we have some confidence that we understand the function of the behaviour. (cf which mussels crabs choose to eat)

Question 6

optimallity modelling experiments

Answer 6

foraging behaviour - crabs eating mussels

• calculate optimal mussel size and compare with actual
• actual optimal matches, but there is still a range

reproductive behaviour - dungflies

• calculate optimal mating time and compare with observed average
• model found to be very close to actual
• actual was a little shorter than predicted

Question 7

experiment testing for conditional behaviour

Answer 7

males deciding to challenging mating males, determined by size, which is gauged by the pitch of croak

• males more hesitant to challenge if croak was deeper;
• tested by using playback of high and low pitched croaks

Question 8

vigilance effect

Answer 8

a way of avoiding predation

larger groups are more likely to spot approaching danger by working cooperatively and having more eyes

eg in meerkats and woodpigeons (v. goshawks)

Question 9

dilution effect

Answer 9

in larger groups, individuals have smaller chances of being the one killed by predators

if there is only 1 in the group –> 100% chance of predation
2 in group –> 50%
4 –> 25%, etc.

Question 10

group geometry OR selfish geometry

Answer 10

defined by Bill Hamilton

for when vigilance offers no advantage

driven by individuals attempting to (selfishly) minimise their DOMAIN OF DANGER, that is the area around themselves, in relation to others

in practice, animals will attempt to position themselves between others, and they will tend to pile up

eg theoretical frogs on a wall AND seals in real life

Question 11

Costs of grouping ie living socially

Answer 11

1. reduced foraging success - eg vultures fighting over carcass OR why tigers hunt solo
2. increased parasitism or predation - eg parasites in cliff swallows reducing chick health and size OR groups being more conspicuous
3. interference with reproduction - eg cuckoldry in red-winged blackbirds

Question 12

benefits of grouping

Answer 12

1. cooperative hunting - eg lions; allows them to catch larger prey
2. finding food - eg osprey
   - they watch what others catch, which informs them (especially if they see that the fish caught are schooling fish) about where they should hunt
3. increased feeding time, due to decreased vigilance time - eg galahs and red-rumped parrots

Question 13

altruism and types of altruism

Answer 13

behaviour that benefits others at cost to oneself;
an “evolutionary puzzle” because individuals do NOT act for the good of the species

unlikely to evolve compared to selfish behaviours

types:

• parental (most common): likely to evolve and genes for caring / nuturing behaviour are likely to be passed on, as young survive
• kin selection (includes parental altruism) - BILL HAMILTON proposed that this favours selection of genes through any kin, based on level of relatedness and the likelihood of benefit over cost
• reciprocity OR reciprocal altruism - for all members of pop, not just relatives (see card)

Question 14

Hamilton’s rule (which determines kin selection)

Answer 14

rB > C
r = relatedness coefficient
B = benefit to recipient
C= cost to donor

Consequence - altruism is more likely the closer the genetic relatedness to the recipient AND the greater the benefit compared to the cost

cf hypothetical situation of a kangaroo raising an alarm about a dingo to her sister…
AND
real scenario of Belding’s ground squirrels - females more likely to raise alarm as they have more relatives in colonies; ALSO, they give calls for sisters and not non-relatives

Question 15

relatedness estimates (ie how animals determine relatedness of others to decide altruism)

Answer 15

• raised by same parents
• similarity to parents
• similarity to self
• familiar v. unfamiliar

Question 16

conditions for reciprocal altruism (reciprocity)

Answer 16

1. cooperation brings net benefit
2. there is opportunity for reciprocity
3. recognition of others and punishment of non-cooperation

eg in vampire bats sharing blood with those who were unlucky in finding blood

Question 17

sexual characters (primary and secondary)

Answer 17

primary - practical, for reproduction

secondary - sexually distinct features that are not essential for reproduction

Question 18

sexual selection (intra and inter)

Answer 18

a subset of natural selection - selection for traits that are solely concerned with increasing mating success compared with other members of the same sex

distinguished from other selection traits because these often decrease odds of survival

intrasexual selection - competition between members of the same sex for access to the other; usual male-male

intersexual selection - choices of one sex among members of the other sex; usually female choice
- eg birds of paradise - male’s showy plumage make them conspicuous and more vulnerable to predation

Question 19

male-male competition (intrasexual selection)

Answer 19

eg hercules beetle - grow huge horns and fight for access to females

eg red deer - same; horns are very cumbersome and make males more vulnerable to predation

eg damselflies - males have special organs to remove rival males’ sperm from female’s productive duct
[NB: this is not only competition between males, but between male and female choice – females have evolved organs to help them store sperm from multiple males and choose which she wants to use to fertilise her eggs]

Question 20

female choice (3 types, with examples)

Answer 20

• of resources (eg katydid) - males produce spermatophore which comprises food AND sperm
• of paternal care (eg house finches) - females choose brightest males who are best feeders and also providers
• of ornamented males who offer neither resources or care (eg satin bowerbirds and peacocks) - female satin bowerbirds choose males with most blue decorations;
• female peacocks choose males with most eye spots on their tail plumage

Question 21

possible reasons for female choice or ornamented males without the benefit of resources or care

Answer 21

1. good genes - ie males with more impressive traits must be in better health and therefore will sire healthier, more robust young
2. Fisher’s hypotheis - ie females who choose more attractive males will have more attractive sons who will have greater mating success and therefore she will have more grandchildren.

Question 22

communication

Answer 22

the process in which a sender uses specially designed signals to modify the behaviour of intended receivers

Signals on average benefit the sender, otherwise they wouldn’t have evolved.

A signal can be targeted at any of an animal’s senses, so that signals can be chemical, acoustic, visual etc.

Question 23

reasons for communication

Answer 23

transmitting:

1. info about the sender (identity, sex, quality & reproductive state)
   - eg male peacocks communicate the qual of their genes through the number of eye spots on their tails
   - what species they are - eg Psyllid bugs “singing” and then dueting with potential mates
2. info about the environment (alarm calls and food info)
   - eg vervet monkeys have specialised alarm calls for predators (see card)
   - eg bees dances comm info about food (see card)

Question 24

vervet monkey alarm call experiment - testing whether the calls functioned like words
AND alternative explanations

Answer 24

alternative explanations:

• fear - diff calls indicated level of fear and drove a unique response
• call leads others to copy behaviour of caller or to see predator themselves

tested by playing back calls and observing behaviour
- in each case, the most common response behaviour was consistent with real calls, meaning the calls did function like words

Question 25

Karl von Frische’s bee experiments - unlocking the meaning behind bee’s symbolic dances

Answer 25

round dance (for food <50m away) -

• others follow dance
• they regurgitate some food
• others can smell the flower

waggle dance (for food >50m away)

• figure eight dance, with straight portion accompanied with waggling
• on flat surface, waggling section points to food source
• on vertical surface, the angle from vertical = the angle from the sun

Question 26

information communicated by bee dances

Answer 26

• direction of food (direction of “waggle” section)
• distance to food (duration of waggle)
• quality of food (speed of return AND no. of repetitions)
• type of food (smell of flower AND regurgitation of food)

In recent experiments, Bees also worked as bio-indicators, as their feeding preferences could be read in their dances – scientists could tell which feeding areas they prefered, which tended to be less urbanised

Question 27

Professor Srinivasan’s bee experiments at the ANU - unlocking how bees communicate distance to food source in waggle dance

Answer 27

distance to food source is encoded in the duration of the waggle

Prof S figured out that bees measure distance based on optic flow

shown by training bees to fly inside a tube with a pattern inside that would artificially increase the perceived optic flow, causing bees to overestimate the distance

Question 28

relatedness percentages

Answer 28

parent-offspring: 50%
sibling-sibling: 50%
half siblings: 25%
grandparent-grandchild: 25%
cousins: 12.5%